I noticed that all devices I connect via the AKiTiO Thunder3 PCIe under perform by about 50% so I got curious and contacted AKiTiO about this issue.

They only had an XPS 13 9350 and said that in the XPS 13 the TB3 controller definitely only connected with x2.3 ( 16Gbps ) and that the HWInfo64 screenshot I send from my XPS 15looks exactly the same as theirs on the XPS 13.

According to HWInfo64 the XPS 15 is indeed equipped with an DSL6340, so is the controller hindered by it's x2.3 or x4.2 pcie connection? Is it a hardware or software ( BIOS/Firmware ) issue?

Yup. Root bridge (port#15) is reporting x2 3.0, which will be 16Gbps. Without eGPU attached does it still report x2 3.0?

If so, that would be a Dell issue with their handshaking with the TB3 controller. If you look at the TB3 controller, is it connected at x4 3.0 to the videocard? I only see a Samsung SSD there. Maybe it runs at x2 3.0 and the uplink bridges are downgraded in speed?

Those XPS machines are very nice. Want full TB3-32Gbps eGPU link speed on them

You only have one Thunderbolt port which is hosted of port15. Now the question is can port15 be mapped back to port13? Or is it still hardwired as port13, port15 (like it was in all previous chipsets up to 4th gen i-core) so that setting x4 port13 would exclude port15 from being active?

If the latter, then it's a hardware limitation requiring a new systemboard and I can see Dell snaking around to avoid that, because by right, they fix or give you a refund for misadvertising. If it's the former, then Dell can release a new BIOS setting port13 to x4.

It would be a pretty big oversight to wire up only 2 lanes from the Intel chipset to the 4-lane TB controller. So fingers crossed, it will just be a BIOS fix.

The Precision M5510 lspci.txt output here shows it too has a port13+port 15 x2 3.0 configuration matching what we see with the XPS 9550.

In this thread we show XPS 9350/9360/9550 and Precision M5510 all run 16Gbps TB3 (half advertised)

I will throw the Dell support a mail explaining the situation, I hope they can just change the mappingin the BIOS...

At least I can now be certain that there is a problem.

Thanks.

Posted by: nando4

You only have one Thunderbolt port which is hosted of port15. Now the question is can port15 be mapped back to port13? Or is it still hardwired as port13, port15 (like it was in all previous chipsets up to 4th gen i-core) so that setting x4 port13 would exclude port15 from being active?

As of Series-6 (2nd gen i-core), lane width is a write-once ME FW bootstrap thats asserted before any software or bootloader loads. I only know @timohour with a 3rd gen i-core Dell e6430 who extracted the BIOS+MEFW, used fitc (Intel tool) to change the lane width, then flashed the BIOS+MEFW back. He had to jumper the audio chip to enable full bios r-w. He got a x2 2.0 eGPU working thiss way. This is a fairly technically challenging process that may not even apply to your system. Intel has been locking down more configuration options each generation.

I'd suggest go the Dell route. There can be no denying now there is a BIOS/hardware misconfiguration resulting in only 16Gbps (x2 3.0) PCIe bandwidth instead of 32Gbps (x4 3.0) that Thunderbolt3 is specced at.

0:1c.0 (port1) is configured as x2 3.0 (16Gbps). The good news is that port can be switched to x4 3.0 mode. The question is whether the lanes 2-4 are electrically wired to the TB3 controller? Something Dell will need to answer since there are no readily available tools for us to switch the BIOS locked link width ourselves. x2 3.0 will give a maximum of 16Gbps bandwidth.

0:1d.0 is configured as x4 3.0. It hosts the Samsung PCIe SSD which runs at x4 3.0. If fancy a NGFF.M2 eGPU and don't mind underside wiring then using this port would give us a 32Gbps eGPU using say a BPlus PE4C 4.1.

Until Dell fix the root hosting port via a new BIOS or systemboard so it run x4 3.0 (32Gbps) rather than the current x2 3.0 (16Gbps), your XPS 9550 will only be able to provide 16Gbps from it's TB3 port. That's regardless of which TB3 enclosure you use.

Posted by: Nier

So will this mean that a Thunderbolt 3 eGPU will have a significantly decreased performance ? I'm getting the Akitio Node for my XPS 15, will the Node run weaker on my notebook as well?

16Gbps vs 32Gbps won't be a drastic loss of performance if using an external LCD. Each netting 87% and 92% performance respectively if using a FHD external LCD and comparing to x16 3.0 REF: techpowerup PCIe scaling.

Where the decreased bandwidth will hurt you most is if using accelerated internal LCD mode, particularly on a 9550's 4K UHD display. That will put a fair load on the Thunderbolt channel.

If your throttling due to CPU+dGPU temps, and you use a eGPU instead of the dGPU, then you have more thermal headroom to then play within. The answer is more likely yes, you'll see an improvement in your current throttling when using an eGPU for gaming.

Posted by: Nier

I apologize if I'm asking too many questions. I'm not familiar with tech. Will this 16Gbps limitation drastically hurt my eGPU's performance then? In other words, will it even be worth getting a Node?

Also another question. I'm having throttling issues with my XPS when gaming. Will an eGPU solve this issue by taking off some of the heat from the laptop?

A small claims court can be used to force Dell to pay a refund on the basis of underperformance of advertised TB3 spec if they don't want to volunteer to do it. Then can get an Acer Nitro 592G or HP ZBook G3 which we can test and submit the same process if (unlikely) have the same problem.

Or get them to swap you for a chunky Dell Precision M7510. I confirm it has a secondary x4 3.0 port, likely the TB3 controller. Precision M3510 is an unknown but has that chunky form factor which may too mean it has such a port.

Dell's response so far lacking any customer satisfaction sensitivity. Disappointing. Glad I held off buying one.

Posted by: julianpoyo

Update on my communication with Dell...

They have denied my return request, and haven't made any indication that they are even willing to acknowledge the problem.

I am not sure they can actually do anything on a technical level, though. They may only have two physical lanes connecting the TB3 chip to the rest of the system, in which case no amount of complaining will change that. The only recourse would be to try and get compensation out of them.